Effect of Different Steeping Conditions on Endosperm Modification and Quality of Distilling Malt

A GDSL-motif Esterase/Lipase Affects Wax and Cutin Deposition and Controls Hull-Caryopsis Attachment in Barley

The cuticle covering aerial organs of land plants is well known to protect against desiccation. Cuticles also play diverse and specialized functions, including organ separation, depending on plant and tissue. Barley shows a distinctive cuticular wax bloom enriched in β-diketones on leaf sheaths, stem nodes and internodes and inflorescences. Barley also develops a sticky surface on the outer pericarp layer of its grain fruit leading to strongly adhered hulls, 'covered grain', important for embryo protection and seed dispersal. While the transcription factor-encoding gene HvNUDUM (HvNUD) appears essential for adherent hulls, little is understood about how the pericarp cuticle changes during adhesion or whether changes in pericarp cuticles contribute to another phenotype where hulls partially shed, called 'skinning'. To that end, we screened barley lines for hull adhesion defects, focussing on the Eceriferum (= waxless, cer) mutants. Here, we show that the cer-xd allele causes defective wax blooms and compromised hull adhesion, and results from a mutation removing the last 10 amino acids of the GDS(L) [Gly, Asp, Ser, (Leu)]-motif esterase/lipase HvGDSL1. We used severe and moderate HvGDSL1 alleles to show that complete HvGDSL1 function is essential for leaf blade cuticular integrity, wax bloom deposition over inflorescences and leaf sheaths and pericarp cuticular ridge formation. Expression data suggest that HvGDSL1 may regulate hull adhesion independently of HvNUD. We found high conservation of HvGDSL1 among barley germplasm, so variation in HvGDSL1 unlikely leads to grain skinning in cultivated barley. Taken together, we reveal a single locus which controls adaptive cuticular properties across different organs in barley.

Optimization using response surface methodology of the soaking and germination time of two rice varieties (Nerica 3 and Nerica L56) grown in the locality of Dschang (West-Cameroon)

Abstract

One of the solutions to increase children's energy intake is the use of amylase-rich flours. This led us to optimize the fluidification capacity of two paddy rice varieties. For that, the Doehlert plane-type response surface methodology was used to optimize the germinating ability of paddy rice flour (varieties Nerica 3 and Nerica L56) to fluidize cassava-based gruels by using two factors: soaking and germination time. The evaluated response was the flow velocity of the gruels. The optimization result showed that, the optimal soaking time was 48 h for the variety Nerica L56 and 12 h for Nerica 3. Concerning the optimal germination time, it was 135 h for both varieties. These conditions have been found to have the best fluidifying capacities for cassava flour-based gruels. The incorporation of 3 g germinated paddy rice flour (Nerica L56 and Nerica 3) and at optimal conditions, allowed us to obtain high flow velocities of the gruels. They were 100.00 mm/30 s and 210.66 mm/30 s respectively for the varieties Nerica L56 and Nerica 3. These flow velocities were similar to the flow velocities predicted by the model for desirabilities of 0.99 and 1.00. In view of all these results, we could therefore recommend the use of these two varieties of rice produced under these conditions to improving flow velocities, dry matter concentrations and energy bulk of the gruels.

Graphic abstract

Optimisation of the production of corn amylase flour from corn Atp and Kassaï varieties for the fluidification and energy density increase of cassava gruel

The energy density of the complementary gruels can be increased by the use of sprouted flours. This led us to determine the conditions for obtaining and using sprouted corn flour for optimal fluidification of fermented cassava flour gruels. To do this, the germinated corn flour (GCF) varieties Atp and Kassaï was produced according to the response surface methodology and the Doehlert plan was used with factors such as soaking (12-48 h) and germination (24-96 h) times. Once obtained, these GCF were used to increase the energy density of cassava flour gruels with flow velocity as response. The Doehlert plan was also used with fermented cassava flour concentration (17.5-30 %) and optimised sprouted corn flour mass (1-5 g) as factors. The experimental design that had been performed indicated that the effectiveness of corn amylase flour to fluidify the gruels depends not only to the conditions of production (soaking and germination) (p < 0.05) but also their incorporation during the preparation (corn amylase-fermented cassava flour) (p < 0.05). The rich corn amylase flour can be obtained by soaking Kassaï and Atp varieties for 20 h and 28 h respectively and germinated for 90.82 h. Application of these GCF during the preparation of fermented cassava flour gruels has shown that to obtain gruels with flow velocities between 100-160 mm/30s, it was necessary to couple 1.16 g of sprouted corn flour variety Kassaï for 26.23 % of fermented cassava flour and 1.12 g of corn flour variety Atp for 25.94 % of fermented cassava flour. The use of these couples has made it possible to multiply the energy density of the gruels by 6.55 and 6.49, respectively. In view of these results, it is therefore advisable to use the germinated corn flours produced under the conditions obtained to fluidise and increase the energy density of the fermented cassava gruels.

In situ study of water uptake by the seeds, endosperm and husk of barley using infrared spectroscopy

Variations in the amount and rates of water uptake influence the seed hydration as well as the modification of the endosperm for industrial uses (e.g., malting). The aim of this study was to investigate and interpret absorption frequencies in the mid infrared (MIR) region associated with water uptake in whole seeds, husk and endosperm of barley seeds during the initial period of soaking in water. Partial least squares (PLS) regression models for the prediction of water uptake in the set of samples yield a coefficient of determination (R(2)) and a standard error in cross validation of 0.75 and 2.57 (% w/w), respectively. The biological implications of this study are that the first stages of germination can be monitored using the information derived from the MIR spectra. These results also demonstrated that whole seeds, endosperm and husk derived from the same variety or genotype have different patterns in the MIR region.

Impact of low hydration of barley grain on β-glucan degradation and lipid transfer protein (LTP1) modifications during the malting process

One of the objectives of the malting industry is to reduce the energy cost during kilning without major effect on malt quality. In this study, the impact of a low hydration steeping process on lipid transfer protein (LTP1) modifications and β-glucan breakdown was evaluated in low (LH) and high (HH) hydrated malts. LTP1 modifications analyzed by MS/MS revealed acylation, glycation, and disulfide bond breakage in both LH and HH malts. LTP1 free amine content measurement and fluorescence of Maillard protein adducts revealed no significant difference between LH and HH malts. Immunolabeling of LTP1 during malting highlighted the diffusion of the protein from the aleurone layer to the endosperm at the end of steeping in both LH and HH malts. By contrast, a significant higher amount of β-glucans was measured in LH malts after five days of germination, whereas no significant difference between LH and HH malts was revealed through immunostaining of β-glucans or evaluation of the endosperm integrity after seven days of germination. The possibility to reduce the effects of a low hydration steeping process on β-glucan hydrolysis by increasing germination time was discussed.